1. Field of the Invention
The present disclosure generally relates to intraluminal support devices. More particularly, the present invention relates to stents having a bow-shaped configuration when expanded.
2. Description of the Related Art
Various types of disease conditions present clinical situations in which a vessel of a patient needs to be artificially supported to maintain an open passageway through which fluids, such as blood, can flow. For example, blood flow through an artery can be impeded due to a build-up of cholesterol on the interior wall of the vessel. Also, vessel walls can be weakened be a variety of conditions, such as aneurysms.
Intraluminal support frames, sometimes referred to as stents, provide an artificial mechanism to support a body vessel. Stents are typically tubular-shaped members that are placed in the lumen of the vessel and, once deployed, exert a radially-outward directed force onto the vessel wall to provide the desired support.
Stents are typically positioned at the point of treatment by navigation through the vessel, and possibly other connected vessels, until the point of treatment is reached. This navigation requires the stent to be able to move axially through the vessel(s) prior to deployment, while still maintaining the ability to exert an outward force on the interior wall once deployed. Accordingly, stents typically have radially collapsed and expanded states. In the collapsed state, the stent has a relatively small diameter that allows it to move axially through the vessel. In the expanded state, the stent has a relatively large diameter that allows it to exert an outward force on the interior wall of the lumen, thereby providing the desired support to the vessel.
Tubular plastic drainage stents, such as biliary stents, pancreatic stents, ureteral stents, etc., are prone to become occluded after only a few months of use, requiring a second procedure to have the old stent replaced. Metal expandable stents offer a wider lumen and are less prone to occlusion over time. However, such stents are difficult to remove and only indicated for palliative treatment end-stage cancer affecting the duct (at least for GI use).
Therefore, a need exists for an expandable and readily removable stent that can also treat benign strictures. A stent that may remain within the patient for six months or more without requiring replacement due to occlusion is also needed.